Most biological organisms are non-linear, time-varying systems with many variables. It is generally difficult to obtain clean, simple input-output relationships or low-variance correlation relationships. There is a growing community of workers who believe that the developing field of dynamical systems, especially its best-known areas of "chaos" and "fractals," offers alternative methods of modeling and studying biological and biomedical relationships more attractive than those associated with linear systems linked to additive noise. The NIH Library, a unit of NCRR, agreed to develop a campus-wide resource for CHAOS and Dynamical Systems programs for the personal computer, in cooperation with the Inter-Institute Chaos Council of the NIH.